Electronic dryer with door flange pickup device



July 25, 1967 JANKE ET AL 3,332,150

ELECTRONIC DRYER WITH DOOR FLANGE PICKUP DEVICE Filed Dec. 22. 1964 4 Sheets-Sheet 1 I N VEN TORS dDozza ldEJazziae fiozz/ardcflfagzzzwezz m' %w z ATTORNEYS July 25, 1967 D. E. JANKE E AL 3,332,160

ELECTRONIC DRYER WITH DOOR FLANGE PICKUP DEVICE 4 Sheets-Sheet p Filed Dec. 22, 1964 I g 623 M J2 :4 36 5 63 29'- g 24 66 54 1' '1 a9 2 225 "m 3 a 453 INVENTORS F 2 DozzajdEd'azzhe 5 [fozuaz dG/fqgzzwezz m &. ATTORNEYS July 25, 1967 JANKE ET AL 3,332,160

ELECTRONIC DRYER WITH DOOR FLANGE PICKUP DEVICE Filed Dec. 22, 1964 4 Sheets-Sheet 5 MEL] INVENTORS E 5 m ATTORNEYS D. E. JANKE ET AL 3,332,160

4 Sheets-Sheet 4 INVENTORS ATTORNEYS ozza rldlilfazzzz .D bozuafidfflagzzzasezz July 25, 1967 ELECTRONIC DRYER WITH DOOR FLANGE PICKUP DEVICE Filed Dec. 22, 1964 United States Patent C) 3,332,160 ELECTRONIC DRYER WITH DOOR FLANGE PICKUP DEVICE Donald E. Janke and Howard C. Magnusen, Benton Harbor, Mich., assignors to Whirlpool Corporation,

Benton Harbor, Mich., a corporation of Delaware Filed Dec. 22, 1964, Ser. No. 420,285 1 Claim. (Cl. 34-45) This invention relates generally to drying apparatus and more particularly relates to a domestic dryer employing an electronic dryness sensing mechanism and including a signal pickup device located on or adjacent a reduced diameter drum collar or flange surroundinging the access opening on the front wall of the drum, thereby reducing cost and wear and improving reliability and service accessibility.

In dryness control systems provided in accordance with the principles of the present invention, the dryness of clothes or any other materials being dried is measured electrically by measuring or sensing the electrical resistance presented between conductors engaged with spaced portions of a mass of clothes, the resistance being low when the clothes are wet and being increased as the clothes approach a dry state. The measured or sensed value of electrical resistance may be used to automatically control the operation of drive, air circulating and heating means incorporated in the dryer.

In accordance with the principles of the present invention, a pickup device of improved reliability, reduced cost and more efiicient operation is provided on a drum collar concentrically disposed with respect to the axis of rotation of the drum and which drum collar is of a much smaller diameter than the normal diameter of the outer drum wall. The drum collar may advantageously constitute an embossment forming the edges of an access opening communicating with the interior of the drum. Thus, the access opening so formed is placed in registry with a door controlled opening in the dryer casing. The pickup device includes an insulating band encompassing the drum collar, a conductive slip ring carried on the insulator band and supported for co-rotation with the dryer by the drum collar and a spring-biased brush carried on the front wall of the casing and engaging the slip ring, thereby facilitating transmittal of signals to electronic interpreting circuitry remote from the drum and located in another portion of the casing.

It is an object of the present invention, therefore, to provide a dryer with electronic sensing mechanism wherein the signal pickup device is of reduced size and improved reliability.

Yet another object of the present invention is to provide a pickup and electrical transfer assembly mounted on the door opening flange of a dryer drum to provide an economical and reliable means for transferring an electrical charge from a control circuit to sensing bands located in a rotating drum.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a structural embodiment of the principles of the present invention is shown by way of example.

As shown on the drawings:

FIGURE 1 is an isometric view of a domestic laundry dryer incorporating the dryness sensing means of the present invention and showing some of the details of construction in a broken-out portion wherein some of the parts have been removed for the sake of clarity; and FIGURE la is an enlarged inset of a portion of FIG- URE 1;

FIGURE 2 is a cross-sectional view with parts removed and with parts shown in elevation to illustrate additional features of the present invention;

FIGURE 3 is a fragmentary front elevational view of the pickup device of FIGURE 2;

FIGURE 4 is an elevational view of the insulator ring provided in accordance with the principles of the present invention;

FIGURE 5 is a fragmentary side elevational view of the ring of FIGURE 3;

FIGURE 6 is a cross-sectional view taken on line VIVI of FIGURE 4; and

FIGURE 7 is a circuit diagram showing an electrical dryness control circuit as embodied in the dryer of FIG- URE l.

Although the dryness control system of the present invention is of general utility, a particularly useful application is made when incorporated in a domestic clothes dryer of the type wherein a batch of clothes is tumbled within a drum rotating on a horizontal axis. An exemplary machine of that type is shown generally in FIG- URE l at 10 and includes a casing 11 having a top wall 12, side walls 13 and a control console 14 on which is mounted a presettable control means shown generally at 16 including an adjustment knob 17 which may be preset by the housewife operator for selecting and initiating a control program. In this particular apparatus, the top wall 12 of the casing 11 is provided with an opening 118 closed by a door 19, thereby to afford selective access to a removable lint filter.

Rotatably mounted within the casing 11 is a clothes tumbling drum shown generally at 20. The drum 2!) includes a front end wall 21 disposed on a radial plane and the drum is further characterized by a circumferentially extending peripheral outer wall 22 which extends circumferentially around the outer peripheral edge of the radial wall 21.

In accordance with the present invention, the casing 11 is characterized by having the front wall 13, formed with an axially inwardly extending flange 23, thereby to form the edges of an access opening. The opening is centrally disposed and may lie within the confines of a recessed portion shown generally at 24 adapted to receive a hinged door whereby the opening may be selectively closed, thereby to provide a door controlled opening in the front wall 13 of the casing 11.

As shown in FIGURE 2, the front wall 13 is specifically embossed to provide an axially extending wall 26 which circumscribes the recessed area 24, which axially extending wall terminates in a radially inwardly extending wall 27 which, in turn, terminates in an axially extending flange 28 which is circular in configuration and actually forms a circular opening 23. The innermost end of the flange or wall 28 is reversely turned as at 29, thereby to provide a smooth edge which will not damage clothes upon engagement therewith.

Referring, further, to FIGURE 2, the drum shown gen erally at 20 has its outer peripheral wall 22 formed with a reversely turned flange 30 nested within a formed flange 31 on the radial wall 21 which constitutes the front wall of the drum 20. The front wall 21 of the drum 20 is particularly characterized by an outwardly projecting flange 32 which forms an access opening 33 communicating the interior of the drum with the access opening 23 in the front wall 13 of the casing 11. As shown in FIG- URE 1a, the axially outwardly projecting flange 32 is concentrically disposed with the axially inwardly projecting flange 28. In accordance with the principles of the present invention, a pickup means is provided for an electrical sensing means and the pickup means comprises generally an insulator ring shown at 34 as well as a slip ring A 36. The pickup means is disposed on the outer surface of the flange 32. In order to retain the same in firm assembly with the flange 32, a retainer ring 37 having a long leg 38 and a short leg 39 is attached to the inside surface of the flange 32, thereby permitting the short leg 39 to overlie the insulator ring 34 and preventing inadvertent displacement thereof. The long leg 38 thus underlies and snugly engages the inside surface of the flange 32.

Disposed at circumferentially spaced points between the ring 37 and the flange 28 are a plurality of bearing blocks 40. In this particular embodiment, two bearing blocks 40 are located at circumferentially spaced points approximately corresponding to the 2 oclock and oclock positions of the flange 28, and each of the bearing blocks 40 is retained in firm assembly with the flange 28 by means of a fastener 41, herein taking the form of a Phillips head screw. Retainer ring 37 slidably contacts the bearing blocks 40 to provide front support for drum 20 during rotation.

It is contemplated by the present invention that sensing means be provided for sensing the dryness of the materials tumbled within the drum 20. To accomplish that end, sensing bands made of suitably conductive material such as stainless steel are shown at 42 and 43. The sensing bands are curved to generally conform to the curved surface of the outer drum wall 22 and extend circumferentially so that two of the bands 42 and 43 may be spaced in axially spaced relation, thereby providing a bridging area through which current may be conducted by clothes engaged against the sensing bands and being tumbled within the interior of the drum 20. More specifically, each sensing band 42 and 43 has a pair of inwardly directed legs 44, 44 and a curved transverse wall portion 46 which faces the inner portion of the drum, thereby to present a smooth engagement surface for contact with the materials within the drum 20. By spacing the sensing bands 42 and 43 so that the clothes carry current between the bands, the clothes become a part of the control cir-' cuit for the dryer. It is the variable resistance of the clothes in the circuit which provides the signal whereby a dryer cycle is terminated.

The sensing bands 42 and 43 are retained in place within the interior of the drum by means of an insulator band made of a non-conductive material such as polypropylene or any other suitable insulating material. The insulating band is shown generally at 47 and is connected in firm assembly with the drum wall 22 by a plurality of fasteners 48. The band 47 is further provided with a pair of spaced strips 49, 49 having lugs which are snapped inside of the legs 44, 44 of the sensing bands 42 and 43, thereby permitting the same to be carried in firm assembly with the band 47.

The sensing bands 42 and 43 and their carrying insulating band 47 may be continuous or in separate plural sectors. In this connection such sectored sensing bands are fully described in the copending application of Donald E. Janke and Sandy C. Gay, Ser. No. 351,425, filed Mar. 12, 1964, now US. Patent No. 3,287,818, and assigned to the present assignee.

Each sensing band is electrically connected to the circuitry of the system by means of appropriate conductor wires. In this connection, the band 42 is connected by means of a conductor wire 50 which is grounded as at 51 to the drum 20. The sensing band 43, on the other hand, is connected by means of a conductor wire 52 which leads to an electrically conductive contact member 53.

Referring now more specifically to FIGURES 4, 5, and 6, considered in conjunction with the other drawings, it will be noted there is provided an insulator ring 34 which is adapted to be stretched over the drum collar provided by the flange 32. The insulating ring 34 is made of an electrically non-conductive material such as polypropylene or the like and is particularly characterized by the formation therein of a plurality of circumferentially spaced ribs 57. Between ribs 57, there are provided chamfered ribs 58. In a typical ring such as that illustrated in FIGURES 4, 5 and 6, there are approximately seventeen circumferentially spaced ribs 57. By virtue of such construction, the ring 34 may be stretched over the drum collar and the spaced ribs 57 and 58 will engage the outer surface of the drum collar or flange 32.

On the outer peripheral surface of the ring 34, there are provided a plurality of radially outwardly extending lugs 59 alternately spaced on opposite sides of the ring, thereby to form a retaining groove in which to seat and retain a slip ring previously identified at 36. The slip ring 36 is made of electrically conductive material such as stainless steel or the like. As shown in FIGURE 2, the contact member 53 has a leg which underlies and engages the slip ring 36, thereby promoting good electrical contact therewith.

In order to provide a pickup relationship with the slip ring 36, there is provided, in accordance with the principles of the present invention, a spring-biased brush construction which is most clearly depicted in FIGURES 2 and 3 of the drawings. It will be noted that the axially extending wall 26 of the front wall 13 of the casing 11 has an opening formed therein through which extends a screw fastener 60, which fastener engages a bracket 61. Connected to the bracket 61 is an electrically conductive spring member 62 generally L-shaped in configuration including a first leg 62a and a second leg 62b. The spring member 62 may be made of spring metal and carries on the free end of the leg 62b a brush-type contact member shown generally at 63 and including a clip 64 and a brush 66 comprising bristles made of electrically conductive material suitable for establishing a continuous wiping contact with the slip ring 36. Since the brush-type contact member 63 is carried on the end of the spring member, it will be continuously biased in the direction of the slip ring in order to promote good electrical contact therewith throughout the rotating operation of the dryer drum 20. The spring member 62 is retained in firm assembly with the bracket 61 by a fastener 67 and has a terminal spade 68 at one end thereof to facilitate connection to a conductor wire 69 leading to interpreting circuitry associated with the sensing means.

Referring now to FIGURE 7, the circuit diagram provided in accordance with the principles of the present invention is shown by means of which the operating components of the dryer 10 may be automatically regulated. A push button switch is shown at 70 and when actuated, current will flow through a line 71, through a door switch 102, through a diode 72 and through a current relay 73. The relay 73 when energized will operate a switch 74 from a first position indicated at 76 to a second position indicated at 77, thereby short circuiting the push button switch 70 and placing the system in normal operation. The relay 73 simultaneously with the actuation of the switch 74 will also close the switches 78 and 79. The closing of the switch 79 energizes a heater 80 by means of which a stream of air circulated throughout the treatment zone of the dryer 10 including the drum 20 is temperature conditioned. The closing of the switch 78 actuates a drive motor 81 having a main winding 82 and a starting winding 83. The starting winding 83 is disconnected by a centrifugal switch 84 upon the motor attaining a substantially steady state speed and simultaneously switch 84 engages contact 84a to provide a parallel circuit to main winding 82 through thermostatic switch 100. The motor 81 (FIGURE 1) drives a blower B through a driving connection 85 in order to drive a stream of air through the treatment zone of the dryer.

The relay 73 has its remaining terminal connected through a silicon controlled rectifier 86 having a cathode connected through a conductor 88 to a neutral terminal N. The silicon controlled rectifier 86 normally has a gate voltage applied thereto through the shunting circuit which includes a resistor 89.

The silicon controlled rectifier 86 is biased so as to be non-conductive when the resistance between a line 90 and ground reaches a predetermined value. In general, the cathode terminal of a diode 91 is connected through the resistor 92, and an adjustable resistor 93 to the dryness sensing assembly by the conductor 90. The variable resistor 93 is connected to the cathode of the silicon controlled rectifier 86 through a resistor 94 and a capacitor 96. The variable resistor 93 is also connected through a resistor 97 and a neon lamp 98 to the base of a transistor 99 having its emitter connected to the cathode of the silicon controlled rectifier 86 and having its collector connected to the gate of the silicon controlled rectifier 86.

In operation, the capacitor 96 is charged by current through the resistors 94, 93 and 92 and the diode 91. With the materials within the drum 20 in a wet stage, the amount of charge on the capacitor 96 is limited by the relatively low resistance of the dryness sensing assembly (shown by legend). However, with the clothes in a drying stage, the resistance of the shunt circuit comprising the dryness sensing assembly increases allowing the charge on the capacitor 96 to increase until the neon lamp 98 fires through the base emitter circuit of the transistor 99. The transistor 99 then being in a conducting stage reduces the voltage of the gate of the silicon controlled rectifier 86 to a value which will not permit conduction during the next half cycle of voltage applied thereto. The silicon controlled rectifier 86 will not conduct as long as the neon lamp 98 is ionized and is conductive which is approximately one-half second in the present embodiment.

The silicon controlled rectifier 86 having ceased conduction, the relay 73 is deenergized opening the switches 74, 78 and 79. Though the heater 80 is deenergized, deenergization of the drive motor 81 will continue through a cool down period regulated by thermostatic switch 100 connecting the drive motor 81 directly to the power line 71.

With relay 73 deenergized, switch 74 returns to its first position at 76 which completes a circuit from capacitor 96 through resistance 87, through switch 74, through diode 72, through relay 73, through silicon controlled rectifier 86, through line 88 and thence to neutral terminal N. This circuit shorts out capacitor 96 and permits any residual charge to be dissipated prior to entrance to the dryer drum by the user. Thus if the user contacts sensing bands 42, 43 he will not receive an electrical shock due to discharge of capacitor 96 through his body. The resistance 87 precludes precharging of the capacitor 96 when switch 70 is closed and prior to energization of relay 73 Which moves switch 74 away from contact 76. Thus at the beginning of each machine cycle, capacitor 96 is completely discharged to provide uniform control circuit conditions for each machine cycle.

Variable resistance 93 is manually controlled by any suitable means and permits selection of clothing dryness. Increasing the resistance 93 limits the charge available to capacitor 96 and thus increases the time required to charge capacitor 96 to the point where neon lamp 98 will fire. With increased drying time, of course, the clothing becomes more and more dry so that by providing a manual control for resistance 93 the resulting dryness of the clothing may be effectively selected by the user.

Although various minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon, all such modifications as reasonably and properly come within the scope of our contribution to the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

A domestic clothes dryer comprising a casing having 6 a front wall,

said front wall being flanged to provide axially inwardly extending inner and outer axial walls and forming the outer boundaries of an access opening,

a hinged door in said access opening at said outer axial wall and being connected to said front Wall for selectively opening and closing said access opening,

a clothes tumbling drum, mounting means journaling said drum for rotation in said casing,

said drum inuluding an outer peripheral wall extending circumferentially and bounding a tumbling zone in which clothes are tumbled upon rotation of said drum,

said drum having a front end wall disposed on a radial plane in spaced parallel adjacency to said casing front wall,

said front end wall of said drum having at its innermost extremities an outwardly projecting flange of reduced diameter relative to said outer peripheral wall and being disposed concentrically circumjacent said inner axial wall of said casing to form a drum opening through which clothes may be placed in said tumbling zone,

.and dryness control apparatus for controlling the operation of the dryer as a function of the dryness of the materials in the drum comprising sensing means in said tumbling zone on said outer peripheral wall for engaging the clothes during a tumbling operation,

pickup means for placing said sensing means in an electrical control circuit and comprising an insulator ring on said outwardly projecting flange of said drum, and

means including a conductive slip ring on said insulator ring and being electrically connected to said sensing means on said outer peripheral wall of said drum, and interpretative circuit means including a spring-biased brush construction comprising a bracket connected to said outer axial wall of said casing,

a spring member made of electrically conductive spring metal and having a first leg connected to said bracket and a second leg extending radially inwardly and disposed adjacent said slip ring,

and a brush-type contact member including a clip and bristles of electrically conductive material on the end of said second leg and establishing continuous Wiping contact with said conductive slip ring,

thereby facilitating transmission of signals from said sensing means in the tumbling Zone to a location remotely situated in the casing relative to said tumbling zone in the drum.

References Cited UNITED STATES PATENTS 1,363,877 12/1920 Imbery 219-389 2,633,646 4/1953 Smith 219-389 2,966,650 12/1960 Earnest 339-3 3,013,143 12/1961 Hayden 339-5 3,122,426 2/1964 Horecky 34-53 X 3,161,479 12/1964 Biderman 34-133 X 3,186,105 6/1965 Nye et a1. 34-45 FREDERICK L. MATTESON, JR., Primary Examiner.

I. I. CAMBY, Assistant Examiner. 

